The present invention generally relates to a cleaning composition. More particularly, the invention relates to a novel cleaning formulation having superior cleaning ability which is readily biodegradable, low in toxicity and volatility, neutral in pH and primarily naturally derived.
General purpose household cleaning compositions for hard surfaces such as metal, glass, ceramic, plastic and linoleum surfaces are commercially available in both powdered and liquid form. Powdered cleaning compositions consist mainly of builder or buffering salts such as phosphates, carbonates, and silicates and although such composition may display good inorganic soil removal, they exhibit inferior cleaning performance on organic soils such as greasy/fatty/oily soils.
Liquid cleaning compositions, on the other hand, have the great advantage that they can be applied onto hard surfaces in a neat or concentrated form so that a relatively high level of surfactant material is delivered directly to the soil. Moreover, it is a rather more straightforward task to incorporate high concentrations of anionic or nonionic surfactant in a liquid rather than a granular composition. For both of these reasons, therefore, liquid cleaning compositions have the potential to provide superior grease and oily soil removal over powdered cleaning compositions.
Nevertheless, liquid cleaning compositions suffer a number of drawbacks which can limit their consumer acceptability. They generally contain little or no detergency builder salts and consequently they tend to have poor cleaning performance on particulate soil and also lack effectiveness under varying water hardness levels. In addition, they can suffer problems relating to homogeneity, clarity, and viscosity when used by consumers. Moreover, the higher in-use surfactant concentration necessary for improved grease and soil removal causes further problems relating to extensive suds formation which requires frequent rinsing and wiping on the part of the consumer.
One solution to the above-identified problems has involved the use of saturated and unsaturated terpenes, in combination with a polar solvent, in order to increase the cleaning effectiveness of the hard surface cleaner and control sudsing. A problem associated with the use of terpenes such as, for example, d-limonene, is that their price, as a raw material, tends to fluctuate wildly. Consequently, the cost to manufacture hard surface liquid cleaners containing terpene solvents is financially disadvantageous to both producers and consumers.
Other solvents which are often employed in hard surface cleaning compositions, instead of terpenes, include those derived from aliphatic, aromatic and halogenated hydrocarbons. Their use, however, is undesirable for environmental reasons due to their limited biodegradation.
Consequently, oil-continuous alkyl ester microemulsions, which are terpene-free, have emerged as a viable option for use in cleaning hard surfaces. These microemulsions are safe and highly-effective at removing graffiti, paint, adhesives, grease, and printing inks from various types of hard surface substrates. When using these methyl ester microemulsions, it is oftentimes desirable that they possess vertical surface cling in order to increase their dwell time on vertical surfaces requiring cleaning.
Microemulsions are optically transparent and thermally stable. This being the case, the use of surfactant thickeners is not an option due to their directly negatively affecting the hydrophilicity of the emulsifier system, thereby destabilizing the optimized formulation. Similarly, colloidal thickeners are also not suitable for use in methyl ester microemulsions because they result in a loss of transparency and sedimentation.
While hydrophibically modified cellulosic gums have been found to thicken oil-continuous methyl ester microemulsions, they impart a hazy appearance to, and eventually precipitate out of, the microemulsion.
It is therefore an object of the present invention to provide a thickened alkyl ester microemulsion which possesses vertical surface cling without any of the above-noted attendant disadvantages.